Old Weblog - October 2004

Darwin bridge scheme for town (Shropshire Star: 01-Oct-04)
A tunnel bridge spanning the River Severn, filled with images depicting the life of Charles Darwin, could be built in Shrewsbury, it has been revealed. The perspex tunnel is just one of dozens of ideas for tourist attractions celebrating the town's most famous son.
How Species Arise (American Scientist: Nov-Dec 2004)
Charles Darwin was so convinced that species arose as an outcome of adaptation driven by natural selection that he did not consider alternatives. He also gave surprisingly little attention to species formation, apparently considering it to be an inevitable consequence of natural selection operating on diverse organisms in a heterogeneous world. The 1930s and 1940s saw the publication of two books focused on species: Theodosius Dobzhansky's Genetics and the Origin of Species, and Ernst Mayr's Systematics and the Origin of Species. Jerry Coyne and Allen Orr's new book, Speciation, is clearly inspired by Dobzhansky's. Coyne and Orr largely ignore the work of those who actually identify, delimit and describe species. Nevertheless, their book, which offers a critical analysis of the enormous literature dealing with speciation, is an impressive achievement of great depth and broad scope. It will be required reading for those studying species and species formation.
Extinct Giant Deer Survived Ice Age, Study Says (National Geographic: 06-Oct-04)
Saber-toothed cats, mastodons, giant sloths, woolly rhinos, and many other big, shaggy mammals are widely thought to have died out around the end of the last ice age, some 10,500 years ago. More recently, however, evidence has emerged that at least two of the spectacular megafauna of the Pleistocene era (1.6 million to 10,000 years ago) clung on until recent times. In the 1990s mammoth remains found on an island north of Arctic Siberia revealed the animals still roamed a tiny corner of the planet just 3,600 years ago. Tantalizingly, this was almost a thousand years after the first pyramids were built in ancient Egypt. Now a new study, published tomorrow in the science journal Nature, suggests that another striking mammal, the Irish elk, likewise lived way beyond the last ice age.
DNA pioneer Professor Maurice Wilkins has died. Nobel Laureate Wilkins, 87, played an important role in the discovery of the double helix structure of DNA, the molecule that carries our "life code". He was awarded the prize in 1962 with Francis Crick and James Watson; their co-discoverer was Rosalind Franklin.
T. rex descended from feathered ancestor (New Scientist: 06-Oct-04)
Chinese palaeontologists have uncovered the most complete fossil yet of an ancestral tyrannosaur, and found that filamentary protofeathers covered its body. Feathers and protofeathers had been found on related dinosaurs, but not on an early tyrannosauroid. The new animal, named Dilong - from the Chinese words for "emperor dragon" - was lightly built and about 1.5 metres long. It lived between 128 and 139 million years ago, predating Tyrannosaurus rex by 60 to 70 million years.
The evolutionary history of head lice is tied very closely to that of their hosts Some head lice infesting people today were probably spread to us thousands of years ago by an extinct species of early human, a genetics study reveals. It shows that when our ancestors left Africa after 100,000 years ago, they made direct contact with tribes of "archaic" peoples, probably in Asia. Lice could have jumped from them on to our ancestors during fights, sex, clothes-sharing or even cannibalism.
See also: If These Lice Could Talk (The Loom: 04-Oct-04)
The Crusade Against Evolution (Wired: October 2004)
In the beginning there was Darwin. And then there was intelligent design. How the next generation of "creation science" is invading America's classrooms.
Scientists believe they have discovered a new group of giant apes in the jungles of central Africa. The animals, with characteristics of both gorillas and chimpanzees, have been sighted in the north of the Democratic Republic of Congo. According to local villagers, the apes are ferocious, and even capable of killing lions.
I must admit, when I originally read this story, I thought it must be nonsense: the discovery of a previously unknown great ape sounded totally implausible. But I later read the story in more depth in New Scientist, and it might not be as far-fetched as I believed. There is certainly intriguing evidence that there might be a new species of giant ape in the Congo, although some scientists believe it to be an already-known sub-species of chimpanzee, while others think it could be a gorilla-chimpanzee hybrid (which, in itself, would be remarkable).
Italian geneticists may have explained how genes apparently linked to male homosexuality survive, despite gay men seldom having children. Their findings also undermine the theory of a single "gay gene". The researchers discovered that women tend to have more children when they inherit the same - as yet unidentified - genetic factors linked to homosexuality in men. This fertility boost more than compensates for the lack of offspring fathered by gay men, and keeps the "gay" genetic factors in circulation. The findings represent the best explanation yet for the Darwinian paradox presented by homosexuality: it is a genetic dead-end, yet the trait persists generation after generation.

See also: How homosexuality is 'inherited' (BBC)

A touchy subject this, claiming as it does that any genetic element of male homosexuality might be nothing more than a byproduct of female sexuality. It's gratifying, however, to see that reports about the study are not being dumbed-down into talk about specific 'gay genes'. Life is far more complex than that.

A 135-million-year-old fossil dinosaur caught apparently grabbing a kip with its head tucked under its forearm has been discovered by scientists in China. It is the earliest known example of an animal unearthed in a bird-like repose. A Nature magazine report says the find suggests the characteristic sleeping posture probably first arose in the dinosaur ancestors of modern birds.
Scientists believe the world's amphibians are facing an unprecedented onslaught of environmental threats. They say as many as 122 species may have become extinct since 1980 and a third of known amphibians face oblivion. Naturalists describe the creatures as sensitive indicators of the health of the wider environment.
A ladybird described as one of the most invasive species is "widespread" in parts of the UK, researchers reveal. A search for Harmonia axyridis was launched by Michael Majerus, of Cambridge University, in early October after one was seen near a pub in Essex. Dr Majerus said the insect posed a "deadly threat" to butterflies, lacewings and many other ladybirds. About 16 sightings were confirmed in the London area, Suffolk, Cambridge, Essex and Kent.
Venomous snails with lightning strikes (New Scientist: 15-Oct-04)
Fish-hunting cone snails harpoon their prey using a pneumatic "gun" to fire venom-filled "teeth" through a long, hollow proboscis, report scientists who examined the process under a microscope. The venom paralyses a fish within 50 milliseconds, allowing the slow-moving snail to engulf and digest it at leisure.
Violence threatens Darwin's paradise (The Observer: 17-Oct-04)
Spanish explorers called them Las Encantadas, the Enchanted Isles, and Charles Darwin used his studies of the islands as the foundation for his theory of natural selection. The Galapagos are among the world's most important scientific treasures, a group of stark volcanic islands fringed by deserted beaches and inhabited by unique varieties of giant tortoise, lizards and birds. Yet life on this idyllic United Nations world heritage site has turned sour. Pitched battles have broken out between fishermen, armed with machetes, and conservationists. Ecuador, which owns the islands, has sent a naval patrol to quell disturbances, while police last week began arresting local men for rioting and assault.
Dinosaurs were not just killed off when the asteroid hit, they were struck down in their prime, suggests a new analysis of dinosaur fossils around the world. "Dinosaurs were just doing incredibly well at the end of the Cretaceous," says David Fastovsky, a palaeontologist at the University of Rhode Island at Kingston. The first dinosaurs evolved about 230 million years ago in the Triassic period. Early dinosaurs were generalists, and had evolved into no more than around 40 genera at any one time up until the late Jurassic, which began about 160 million years ago. But then diversity soared in the Cretaceous which followed. Fastovsky’s team has established that at least 245 dinosaur genera lived during the late Cretaceous period, from 99 to 65 million years ago.
The old wives' tale has it that women who want to have sons should eat meat and salty food or make love standing up during a quarter moon. But the real answer for women could be a lot simpler than that: just make sure you are living with your partner. An American doctor has found that women are more likely to give birth to boys if they are married or living with a man at the time of conception. The results are the first evidence that living arrangements can affect the human sex ratio at birth, and could explain the fall in the number of boy babies in some developed countries in the past 30 years.
Recount slashes number of human genes (New Scientist: 20-Oct-04)
Humans have just 20,000 to 25,000 genes - well down on previous estimates of 27,000 to 40,000, says the latest analysis of the gene-containing portion of the human genome. And a separate study has found detailed flaws in "shotgun" sequencing, the more rapid of the two methods used to sequence genomes. The latest gene count reveals that researchers overestimated the number of genes lurking in heavily-duplicated regions of the human genome, which are extremely tricky to sequence because they are repeated DNA sequences… By analysing these "difficult" duplicated regions, Waterston and his colleagues in the International Human Genome Sequencing Consortium discovered that 1183 of the genes had recently been acquired through duplication and the evolution of pre-existing genes. "These segments are rapidly evolving and appear to be particularly prominent in primate and great ape genomes," says Waterston. "We can at last begin to learn about these and find out how they’ve contributed to evolution and disease."
A 121 million-year-old baby arboreal bird, fossilised while still curled in its egg, has been found in China, Science magazine reports this week. The fossil is thought to be the most ancient unborn bird ever discovered.
Platypus sex is XXXXX-rated (New Scientist: 24-Oct-04)
The weird and wonderful duck-billed platypus just got even more weird and more wonderful. Platypuses are famous for laying eggs yet producing milk, having a bird-like bill and a skeleton with reptilian features. Now it turns out that the mammal has an equally eye-catching way of deciding its sex, according to a study by Frank Grützner and Jenny Graves at the Australian National University in Canberra, and colleagues. In most mammals, including humans, sex is decided by the X and Y chromosomes: two Xs create a female, while XY creates a male. In birds, the system is similar: ZW makes for a female, while ZZ makes for a male. But in platypuses, XXXXXXXXXX creates a female, while XYXYXYXYXY creates a male. In other words, rather than a single chromosome pair, platypuses have a set of ten-chromosomes that determine their sex.
Scientists have discovered a new and tiny species of human that lived in Indonesia at the same time our own ancestors were colonising the world. The three-foot (one-metre) tall species - dubbed "the Hobbit" - lived on Flores island until at least 12,000 years ago… The discovery has been hailed as one of the most significant of its type in decades.

The archaeological/anthropological story of the year.

See also:
Dolphins' big brains evolved in spurts (New Scientist: 29-Oct-04)
Dolphins have evolved surprisingly big brains over the last 47 million years, according to the largest fossil study ever done on the animals. The growth - which occurred in two spurts - may shed light on how humans became so brainy.
An fine example of Punctuated Eek-eek-eek-eek-equilibrium!
Was Darwin Wrong? (National Geographic, November 2004 edition)
The work of the 19th-century English naturalist shocked society and revolutionized science. How well has it withstood the test of time?

Teaser for November's National Geographic special. One for framing and putting on the study wall, methinks.

For an amusing take on this edition of National Geographic, see Official November 2004 National Geographic Appreciation Station (Iron Circus weblog)

All English elm trees could be descended from a single tree brought here by the Romans, scientists say. Spanish researchers who examined DNA from English elm told Nature magazine they found almost no difference between elm from Britain, Spain and Italy. The findings support historical evidence suggesting the English elm is identical to the Italian Atinian elm.
Which explains why our elms were so susceptible to disease.